Template Class ObservedVariable

Defined in File observed-variables.h

Class Documentation

template<typename T, std::uint8_t Observers = 1> class ObservedVariable

Adds immediate observer callbacks to synchronized, versioned storage.

Every set() invokes observers on the calling thread, even when the value is unchanged. Waiters wake only for a changed value. Use CE::State::VersionedVariable directly when callback thread affinity is undesirable. Callbacks run in array order after releasing the storage mutex, with this set’s argument, not a later snapshot. Their const reference is borrowed for the call. Concurrent/reentrant sets can overlap callbacks; callbacks protect their own targets. A throw propagates after publication and skips later observers without rollback.

Template Parameters:

T – Value type satisfying VersionedVariable’s copy/assignment/equality requirements.
Observers – Fixed callback count, including zero; this object is noncopyable/nonmovable.

Public Types

using Callback = std::function<void(const T&)>: Immediate observer receiving a borrowed reference to this set’s argument.

Public Functions

inline explicit ObservedVariable(T value, std::array<Callback, Observers> observers)

Stores an initial value and fixed ordered observer list.

Parameters:

value – Initial owned value, moved into synchronized storage at revision zero.
observers – Owned callable array; empty entries are skipped and borrowed captures must remain alive. Construction invokes no observer. Observers may be zero; no dynamic registration is provided.

inline ObservedVariable &operator=(T value)

Publishes through set() and returns this observer wrapper.

Parameters:: value – New value; observers run even for an equal value.
Returns:: This object; observer exceptions propagate after publication.

inline void set(T value)

Publishes the candidate, then calls each nonempty observer in array order.